The Substance Abuse and Mental Health Services Administration (SAMHSA) has established a clear vision for its work -- a life in the community for everyone. To realize this vision, the Agency has sharply focused its mission on building resilience and facilitating recovery for people with or at risk for mental or substance use disorders. SAMHSA is gearing all of its resources -- programs, policies and grants -- toward that outcome. http://www.samhsa.gov/

The most common drug addictions are to legal substances such as:

• Caffeine
• Nicotine in the form of tobacco, particularly cigarettes
• Alcohol

http://en.wikipedia.org/wiki/Drug_addiction

Wikipedia on treatment: http://en.wikipedia.org/wiki/Drug_addiction#Treatment